Simultaneously fabricating a high voltage transistor and a finFET

ABSTRACT

Forming a semiconductor layer on a semiconductor substrate, a top surface of the semiconductor layer above a fin in a second region is higher than a top surface of the semiconductor layer in a first region, etching the semiconductor layer and a mask in the first region to expose a top surface of the semiconductor substrate to form a first stack, and etching the semiconductor layer and the mask in the second region to expose a top surface of the fin to form a second stack, epitaxially growing a semiconductor material on a top surface of the fin not covered by the second stack, recessing the first and second stack to expose a top surface of the semiconductor layer, a portion of the mask remains above the semiconductor layer in the first stack, top surfaces of each of the first and second stacks each are substantially flush with one another.

BACKGROUND

The present invention generally relates to semiconductor manufacturing,and more particularly to fabricating high voltage transistors and fieldeffect transistors (FET).

Complementary Metal-oxide-semiconductor (CMOS) technology is commonlyused for FETs as part of advanced integrated circuits (IC), such ascentral processing units (hereinafter “CPUs”), memory, storage devices,and the like. A high voltage transistor is a structure that can operateat a higher voltage than a CMOS FET.

A high voltage transistor can be used as a power converter, as a selecttransistor for an anti-fuse, for external drivers, among other uses.

SUMMARY

According to one embodiment of the present invention, a method isprovided. The method may include conformally forming a semiconductorlayer on a semiconductor substrate having a first region and a secondregion, where a top surface of the semiconductor layer above a fin inthe second region is at a greater height than a top surface of thesemiconductor layer in the first region, where the height is measuredrelative to a top surface of the semiconductor substrate, forming a maskon the semiconductor layer, etching the semiconductor layer and the maskin the first region to expose a top surface of the semiconductorsubstrate to form a first stack, and etching the semiconductor layer andthe mask in the second region to expose a top surface of the fin to forma second stack, epitaxially growing a semiconductor material on a topsurface of the fin which is not covered by the second stack, recessingthe first and second stack to expose a top surface of the semiconductorlayer in the second stack, where a portion of the mask remains above thesemiconductor layer in the first stack, where top surfaces of each ofthe first and second stacks each are substantially flush with oneanother, forming a first pair of sidewall spacers on opposite sidewallsof the first stack, and forming a gate adjacent to and in direct contactwith at least one of the first pair of sidewall spacers.

According to another embodiment, a method is provided. The method mayinclude conformally forming a semiconductor layer on a semiconductorsubstrate having a first region and a second region, where a top surfaceof the semiconductor layer above a fin in the second region is at agreater height than a top surface of the semiconductor layer in thefirst region, where the height is measured relative to a top surface ofthe semiconductor substrate, forming a mask on the semiconductor layer,etching the semiconductor layer and the mask in the first region toexpose a top surface of the semiconductor substrate to form a firststack, and etching the semiconductor layer and the mask in the secondregion to expose a top surface of the fin to form a second stack,epitaxially growing a semiconductor material on a top surface of the finwhich is not covered by the second stack, and recessing the first andsecond stack to expose a top surface of the semiconductor layer in thesecond stack, where a portion of the mask remains above thesemiconductor layer in the first stack, where top surfaces of each ofthe first and second stacks each are substantially flush with oneanother.

According to another embodiment, a structure is provided. The structuremay include a semiconductor substrate, where the semiconductor substratehas a first region and a second region, where the first region includesa channel, where the channel includes a semiconductor layer, where a topsurface of the semiconductor layer is essentially coplanar with a bottomsurface of a mask, a gate including a sidewall spacer, where a sidewallof the sidewall spacer is essentially coplanar with a sidewall of thesemiconductor, and a source drain region, the second region includes anepitaxially grown source drain region above and in direct contact with afin of the semiconductor substrate, a second region sidewall spacer,where the second region sidewall spacer has a sidewall which isessentially coplanar with a sidewall of the epitaxially grown sourcedrain region, and a gate, where a top surface of a gate contact isessentially coplanar with a top surface of the mask in the first region,and where the sidewall spacer of the first region serves as a gatedielectric, and is the same material and thickness as the second regionsidewall spacer.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the invention solely thereto, will best be appreciatedin conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a semiconductor structure at anintermediate stage of fabrication, according to an exemplary embodiment;

FIG. 2 is a cross-sectional view of the semiconductor structure andillustrates the formation of a first, second, third and fourth stack,according to an exemplary embodiment;

FIG. 3 is a cross-sectional view of the semiconductor structure andillustrates the formation of sidewall spacers and depicting an epitaxialgrowth, according to an exemplary embodiment;

FIG. 4 is a cross-sectional view of the semiconductor structure andillustrates the formation of a second dielectric layer, according to anexemplary embodiment;

FIG. 5 is a cross-sectional view of the semiconductor structure andillustrates the selective removal of a portion of the first, second,third and fourth stacks, according to an exemplary embodiment;

FIG. 6 is a cross-sectional view of the semiconductor structure andillustrates the removal of the second, third and fourth stacks,according to an exemplary embodiment;

FIG. 7 is a cross-sectional view of the semiconductor structure andillustrates the formation of a dielectric and a conductor, according toan exemplary embodiment;

FIG. 8 is a cross-sectional view of the semiconductor structure andillustrates the recess of the dielectric and the conductor, and theformation of a dielectric cap, according to an exemplary embodiment;

FIG. 9 is a cross-sectional view of the semiconductor structure andillustrates the formation of an opening and a contact, according to anexemplary embodiment; and

FIG. 10 is a cross-sectional view of the semiconductor structure andillustrates FIG. 9 in an alternate view, according to an exemplaryembodiment.

Elements of the figures are not necessarily to scale and are notintended to portray specific parameters of the invention. For clarityand ease of illustration, scale of elements may be exaggerated. Thedetailed description should be consulted for accurate dimensions. Thedrawings are intended to depict only typical embodiments of theinvention, and therefore should not be considered as limiting the scopeof the invention. In the drawings, like numbering represents likeelements.

DETAILED DESCRIPTION

Detailed embodiments of the claimed structures and methods are disclosedherein; however, it can be understood that the disclosed embodiments aremerely illustrative of the claimed structures and methods that may beembodied in various forms. This invention may, however, be embodied inmany different forms and should not be construed as limited to theexemplary embodiments set forth herein. In the description, details ofwell-known features and techniques may be omitted to avoid unnecessarilyobscuring the presented embodiments.

References in the specification to “one embodiment”, “an embodiment”,“an example embodiment”, etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

It will be understood that when an element as a layer, region orsubstrate is referred to as being “on” or “over” another element, it canbe directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present. Also the term“sub-lithographic” may refer to a dimension or size less than currentdimensions achievable by photolithographic processes, and the term“lithographic” may refer to a dimension or size equal to or greater thancurrent dimensions achievable by photolithographic processes. Thesub-lithographic and lithographic dimensions may be determined by aperson of ordinary skill in the art at the time the application isfiled.

In the interest of not obscuring the presentation of embodiments of thepresent invention, in the following detailed description, someprocessing steps or operations that are known in the art may have beencombined together for presentation and for illustration purposes and insome instances may have not been described in detail. In otherinstances, some processing steps or operations that are known in the artmay not be described at all. It should be understood that the followingdescription is rather focused on the distinctive features or elements ofvarious embodiments of the present invention.

The formation of the high voltage transistor according to the presentdisclosure can be implemented in the back-end-of-line (BEOL), and iscompatible with semiconductor manufacture process flows. The presentinvention thus allows the high voltage transistor to be fabricatedduring manufacture of CMOS FETs and other circuitry at the same time,thus advantageously reducing processing costs compared to manufacturinghigh voltage transistors fabricated during an alternate process flow.

The present invention generally relates to semiconductor manufacturingand more particularly to fabricating a high voltage transistor and afield effect transistors (FET) in the same process flow. One way tofabricate both the high voltage transistor and the FET may includefabricating a polysilicon layer which covers a fin. A top of thepolysilicon layer may be at a higher level from a substrate compared tothe polysilicon layer directly on the substrate where there is not afin. A high voltage transistor may be fabricated in a portion of thearea where there is not a fin. A mask may be deposited on the substrate,covering the polysilicon layer. Upon subsequent processing, an etch mayremove the mask in an area of the fin and a portion of the mask mayremain in an area of the high voltage transistor, due to the higherlevel of the polysilicon layer and the mask covering the fin. Aremaining portion of the mask may protect the high voltage transistorfrom several processing steps in the area of the fin, allowing separateprocessing in the area of the fin and the area of the high voltagetransistor. The resulting structure may include a high voltagetransistor and an FET. A higher level metal layer including a wiringlevel may be formed on the resulting structure and may contain circuitryto control the high voltage transistor and the FET.

A method of manufacturing a semiconductor with one or more high voltagetransistors and one or more FETs, or an array of FETS, in the sameprocess flow is described in detail below by referring to theaccompanying drawings in FIGS. 1-10, in accordance with an illustrativeembodiment.

Referring now to FIG. 1, a semiconductor structure 100 (hereinafter“structure”) is shown according to an exemplary embodiment. Thestructure 100 may include a substrate 102. The substrate 102 may includean inactive region 200 and an active region 300. The inactive region 200may include an insulator (e.g., oxide) on a substrate. A fin 104 may beformed on the substrate 102 in the active region 300. The active region300 may include a doped region below the fin 104. Additional structures,(not shown), may be formed on the substrate 102. In an embodiment, anisolation region may be formed between the inactive region 200 and theactive region 300.

The structure 100 of FIG. 1 may be formed or provided. At this step ofthe manufacturing process, the beginning structure of a field effecttransistor (hereinafter “FET”) 302 is shown. The FET 302 may preferablybe fabricated in the active region 300. The FET 302 may be formed on thesubstrate 102 as shown in FIG. 1 according to techniques known in theart.

A FinFET device may include a plurality of fins formed in a wafer; agate covering a portion of the fins, where the portion of the finscovered by the gate serves as a channel region of the device andportions of the fins extending out from under the gate may serve assource and drain regions of the device; and a pair of device spacers onopposite sides of the gate. It should be noted that the inventiondisclosed below may be fabricated using either a replacement gate orgate last process flow, or a gate first process flow. A replacement gateprocess flow will be relied on for the description provided below.

In a replacement gate (RG) fabrication approach, the substrate 102 maybe patterned and etched to form active device region (e.g., fins). Next,one or more dummy gates may be formed in a direction perpendicular tothe length of the fins. For example, the dummy gates may be pattered andetched from a polysilicon layer. A pair of sidewall spacers, can bedisposed on opposite sidewalls of the dummy gates. The dummy gates andthe pair of sidewall spacers may then be surrounded by an inter-leveldielectric. Later, the dummy gates may be removed from between the pairof device spacers. This creates an opening between the pair of devicespacers where a metal gate, may then be formed between the pair ofdevice spacers. Optionally, a gate dielectric may be configured belowthe metal gate.

The substrate 102 may be a bulk substrate, which may be made from any ofseveral known semiconductor materials such as, for example, silicon,germanium, silicon-germanium alloy carbon-doped silicon-germanium alloy,and compound (e.g. III-V and II-VI) semiconductor materials.Non-limiting examples of compound semiconductor materials includegallium arsenide, indium arsenide, and indium phosphide. In otherembodiments, the substrate 102 may be, for example, a layeredsemiconductor such as Si/SiGe, a silicon-on-insulator, or aSiGe-on-insulator, where a buried insulator layer separates a basesubstrate from a top semiconductor layer. In such cases, components ofthe structure 100 may be formed in or from the top semiconductor layerof the SOI substrate. Typically the substrate 102 may be approximately,but is not limited to, several hundred microns thick. The substrate 102may include additional structures (not shown) such as shallow trenchisolation (STI) and/or doped regions.

In an embodiment, the FET 302 may be fabricated as a FinFET device,nanowire device, planar MOSFET, or any suitable combination of thosedevices. In general, a FinFET device may include a plurality of finsformed in the substrate 102. In the present embodiment, a gate may beperpendicular to and cover a portion of one or more fins. The portion ofthe fin covered by the gate may serve as a channel region of the FET302. Portions of the fin extending out from under each of the gates mayserve as source and drain regions for the FET 302. In this example, theFinFET may be formed from the substrate 102 using known photolithographyand etch processes. It should also be noted, that in the context ofFinFET devices the portion of the substrate 102 illustrated in thefigures represents a cross-section view along a length direction of thefin 104. A dielectric layer 106 and a semiconductor layer 108 areillustrated as being disposed directly on top of the fin 104, accordingto the present embodiment. In an embodiment, the FET 302 may have avertical thickness, or height, ranging from about 20 nm to 100 nm, andranges there between, although a thickness less than 20 nm and greaterthan 100 nm may be acceptable. The semiconductor layer 108 may includesilicon, silicon germanium, germanium, or any other semiconductormaterials. The semiconductor layer 108 can be deposited as amorphous orpolycrystalline (poly).

The dielectric layer 106 may be conformally formed directly on theexposed top surfaces of the structure 100, according to an exemplaryembodiment. The dielectric layer 106 may include a dielectric materialsuch as an oxide, nitride, oxynitride, silicon carbon oxynitride,silicon boron oxynitride, high-k dielectric, or any combination thereof.In an embodiment, the dielectric layer 106 may be deposited usingtypical deposition techniques, for example, nitridation, atomic layerdeposition (ALD), molecular layer deposition (MLD), chemical vapordeposition (CVD), physical vapor deposition (PVD), and spin ontechniques. In an alternate embodiment the dielectric layer 106 may bedeposited using thermal oxidation as a deposition technique. In thisalternate embodiment, the dielectric layer 106 is formed on exposedsurfaces of the fin 104, and the dielectric layer 106 is not formed inthe inactive region 200 which is already covered by dielectric material(e.g., oxide). In an embodiment, the dielectric layer 106 may includeone or more layers. In an embodiment, the dielectric layer 106 may havea vertical thickness, or height, ranging from about 2 nm to 20 nm, andranges there between, although a thickness less than 2 nm and greaterthan 20 nm may be acceptable.

The semiconductor layer 108 may be conformally formed directly on theexposed top surfaces of the structure 100, according to an exemplaryembodiment. The semiconductor layer 108 may be formed using knowntechniques. The material of the semiconductor layer 108 may includepolycrystalline or amorphous silicon, germanium, silicon germanium,carbon nanotube, graphene, or any suitable combination of thesematerials. The semiconductor layer 108 material may further includedopants that are incorporated during or after deposition. Thesemiconductor layer 108 may be deposited using typical depositiontechniques, for example, atomic layer deposition (ALD), molecular layerdeposition (MLD), chemical vapor deposition (CVD), physical vapordeposition (PVD), and spin on techniques. In an embodiment, thesemiconductor layer 108 may be deposited via CVD. In an embodiment, thesemiconductor layer 108 may include one or more layers. In anembodiment, the semiconductor layer 108 may have a vertical thickness,or height, ranging from about 50 nm to 150 nm, and ranges there between,although a thickness less than 50 nm and greater than 150 nm may beacceptable.

It should be noted that a difference in a height of a top surface of thesemiconductor layer 108 in the active region 300 may be a height ‘h’,compared to a height of a top surface of the semiconductor layer 108 inthe inactive region 200, when compared to a top surface of the substrate102. This difference in height ‘h’ may be due to the conformaldeposition of the semiconductor layer 108 on the fin 104 in the activeregion 300 compared to the conformal deposition of the semiconductorlayer 108 on an area in the inactive region 200 which does not have afin 104.

In an embodiment, the semiconductor layer 108 may serve as a channel inthe inactive region 200, for a high voltage transistor.

A mask 110 may be conformally formed on the semiconductor layer 108. Themask 110 may be a hardmask which directly covers the inactive region 200and the active region 300. The mask 110 may be deposited and polishedusing a chemical mechanical polishing (CMP) technique, as illustrated. Avertical thickness of the mask 110 in the inactive region 200 may begreater than a vertical thickness of the mask in the active region 300,as a result of the CMP and the height ‘h’ as described above. In anembodiment, a difference in the vertical thickness difference of themask 110 in the inactive region 200 and the vertical thickness of themask 110 above the fin 104 in the active region 300 may range from about10 nm to 30 nm, and ranges there between, although a difference lessthan 10 nm and greater than 30 nm may be acceptable. In an embodiment,the mask 110 may have a vertical thickness, or height, ranging fromabout 50 nm to 300 nm, and ranges there between, although a thicknessless than 50 nm and greater than 300 nm may be acceptable.

Referring now to FIG. 2, a first stack 204, a second stack 304, a thirdstack 306 and a fourth stack 308 may be formed using any knownpatterning technique. In an embodiment, the stacks are formed bylithography and etch techniques. Alternatively, the first, second, thirdand fourth stacks 204, 304, 306, 308 may be patterned by sidewall imagetransfer (SIT) technique. Portions of the dielectric layer 106, thesemiconductor layer 108 and the mask 110 are removed between the first,second, third and fourth stacks 204, 304, 306, 308. The first stack 204may be in the inactive region 200 and the second stack 304, third stack306 and the fourth stack 308 may be in the active region 300. The first,second, third and fourth stacks 204, 304, 306, 308 may each have thesame or different horizontal widths. In an embodiment, a horizontalwidth of the first stack 204 may range from 50 nm to 150 nm, although awidth less than 50 nm and greater than 150 nm may be acceptable. Ahorizontal width of the second, third and fourth stacks 304, 306 and308, may range from 10 nm to 50 nm, although a width less than 10 nm andgreater than 50 nm may be acceptable. The first stack 204 may beadjacent to an exposed top surface of the substrate 102. The third stack306 may be adjacent to an exposed top surface of the fin 104. The secondand fourth stacks 304, 308, may each have a first side adjacent to anexposed top surface of the substrate 102 and may each have a second sideadjacent to an exposed top surface of the fin 104.

The beginning structure of a high voltage transistor 202 is shown. Thehigh voltage transistor 202 may preferably be fabricated in the inactiveregion 200. The high voltage transistor 202 may be formed on thesubstrate 102 as shown in FIG. 2 according to techniques known in theart.

Referring now to FIG. 3, sidewall spacers may be formed. A first pair ofsidewall spacers 112 of the first stack 204 may be formed within theinactive region 200, on opposite sidewalls of the first stack 204. Asecond pair of sidewall spacers 112 may be formed on opposite sidewallsof the second stack 304, a third pair of sidewall spacers 112 may beformed on opposite sidewalls to the third stack 306, and a fourth pairof sidewall spacers 112 may be formed on opposite sidewalls of thefourth stack 308. The first, second, third and fourth pairs of sidewallspacers 112 may be formed by conformally depositing or growing adielectric, followed by an anisotropic etch that removes the dielectricfrom the horizontal surfaces of the structure 100, while leaving it onthe sidewalls of first, second, third and fourth stacks 204, 304, 306,308. In an embodiment, the first, second, third and fourth pairs ofsidewall spacers 112 may include any dielectric material such as siliconoxide, silicon oxynitride, silicon nitride, SiBCN, SiOC, low-kdielectric or any combination of these materials. The first, second,third and fourth pairs of sidewall spacers 112, may include a singlelayer; however, the first, second, third and fourth pairs of sidewallspacers 112, may include multiple layers of dielectric material. In anembodiment, the first, second, third and fourth pairs of sidewallspacers 112, may be silicon nitride. In an embodiment, the first,second, third and fourth pairs of sidewall spacers 112 may have alateral thickness ranging from about 3 nm to about 20 nm, and rangesthere between, although a thickness less than 3 nm and greater than 20nm may be acceptable.

In an embodiment, the first pair of sidewall spacers 112 may serve as agate dielectric for the high voltage transistor 202.

As illustrated, the first, second, third and fourth pairs of sidewallspacers 112 may be recessed due to overetch. A directional etch, forexample an anisotropic vertical etch process such as a reactive ion etch(RIE), may be performed, and may remove an upper portion of the first,second, third and fourth pairs of sidewall spacers 112.

An epitaxy layer 114 may be formed in an opening between the secondstack 304 and the third stack 306, as well as in an opening between thethird stack 306 and the fourth stack 308. The epitaxy layer 114 may beformed by selective deposition on exposed surfaces of the fin 104.Examples of various epitaxial growth techniques used in forming theepitaxy layer 114 may include, for example, rapid thermal chemical vapordeposition, low energy cluster beam deposition, ultra-high vacuumchemical vapor deposition, and atmospheric pressure chemical vapordeposition. The epitaxy layer 114 may be formed directly on the fin 104.The epitaxy layer 114 may be doped during epitaxy process (in-situdoping) or after epitaxy process (ex-situ doping). A non limiting listof exemplary epitaxial materials are: silicon germanium alloy (SiGe),Silicon (Si), in-situ boron doped SiGe or Si, in situ phosphorus orarsenic doped Si or SiGe, with doping levels ranging from 1E19/cm³ to1.5E21 cm³, with 4E20 cm³ to 9E20 cm³ dopant levels preferred. Theepitaxy layer 114 may serve as source/drain regions of the FET 302 inthe active region 300. Thermal anneal such as laser anneal, rapidthermal anneal, flash anneal may be performed to activate dopants andformed junctions. In an embodiment, silicide may be formed on a surfaceof the epitaxy layer 114 to reduce the contact resistance of the FET302.

Referring now to FIG. 4, a second dielectric layer 116 may be formed.The second dielectric layer 116 may also be referred to as amiddle-of-line (hereinafter “MOL”) dielectric. The second dielectriclayer 116 may be formed directly on the exposed top surfaces of thestructure 100, according to an exemplary embodiment. The seconddielectric layer 116 may be made from an insulator material such as anoxide, nitride, oxynitride, silicon carbon oxynitride, silicon boronoxynitride, low-k dielectric, or any combination thereof. The seconddielectric layer 116 may be deposited using typical depositiontechniques, for example, atomic layer deposition (ALD), molecular layerdeposition (MLD), chemical vapor deposition (CVD), physical vapordeposition (PVD), high density plasma (HDP) deposition, and spin ontechniques. In an embodiment, the second dielectric layer 116 mayinclude one or more layers. The second dielectric layer 116 may bepolished using a chemical mechanical polishing (CMP) technique, asillustrated. The second dielectric layer 116 may be formed between thefirst, second, third and fourth stacks 204, 304, 306, 308. The seconddielectric layer 116 between the first stack 204 and the second stack304 may have a bottom surface substantially flush with a top surface ofthe substrate 102. The second dielectric layer 116 between the secondstack 304 and the third stack 306 may have a bottom surfacesubstantially flush with a top surface of the epitaxy layer 114. Thesecond dielectric layer 116 between the third stack 306 and the fourthstack 308 may have a bottom surface substantially flush with a topsurface of the epitaxy layer 114.

Referring now to FIG. 5, a portion of the mask 110 may be removed via ananisotropic vertical etch process such as a reactive ion etch (RIE), viaan isotropic etch process such as hot phosphoric acid to etch siliconnitride, or via the combination of any suitable etch process. The totaletch amount is equal or greater than the vertical thickness of the mask110 in the active region 300 before etch, but less than the verticalthickness of the mask 110 in the inactive region 200 before etch. As aresult, the mask 110 is removed in the active region but a portion ofthe mask 110 remain in the inactive region. The mask 110 of the second,the third and the fourth stacks 304, 306, 308, may be removed until atop surface of the semiconductor layer 108 is exposed. A top portion ofthe mask 110 in the first stack 204 may be removed until a top surfaceof the mask 110 in the first stack is substantially flush with a topsurface of the semiconductor layer 108 of the second, the third and thefourth stacks 304, 306, 308. A remaining portion of the mask 110 in thefirst stack 204 remains due to the height ‘h’, the difference in aheight of a top surface of the semiconductor layer 108 in the activeregion 300, compared to a height of a top surface of the semiconductorlayer 108 in the inactive region 200, relative to a top surface of thesubstrate 102.

Referring now to FIG. 6, the second, the third and the fourth stacks304, 306, 308, may be selectively etched and removed via any suitableetch process such as RIE, plasma etch, wet etch, or any suitablecombination of those etch processes. A portion of the semiconductorlayer 108 and a portion of the dielectric layer 106 may be removedselective to the mask 110 and the second dielectric layer 116, resultingin a first opening 404, a second opening 406 and a third opening 408,respectively. A bottom of both the first opening 404 and the thirdopening 408 may be an exposed top surface of the substrate 102. A sideportion of the fin 104 may be exposed in both the first opening 404 andthe third opening 408. A top of the fin 104 may be exposed in both thefirst opening 404 and the third opening 408. A bottom of the secondopening 406 may be an exposed top surface of the fin 104.

The remaining portion of the mask 110 in the first stack 204 protectsthe first stack 204 during the selective etching of the second, thirdand fourth stacks 304, 306, 308.

Referring now to FIG. 7, a dielectric 118 and a conductor 120 may beformed in the first stack 204, and the first, second and the thirdopenings 404, 406, 408. The dielectric 118 in the third opening 406 mayserve as a gate dielectric of FET 302, and the conductor 120 in thethird opening 406 may serve as a gate of the FET 302. The conductor 120in the third opening 406 may further include a workfunction settinglayer to set a threshold voltage of the FET 302 and another processinglayer may be formed to reduce a gate resistance of the FET 302.

The dielectric 118 may be first conformally deposited using typicaldeposition techniques, for example, atomic layer deposition (ALD),molecular layer deposition (MLD), chemical vapor deposition (CVD),physical vapor deposition (PVD), and spin on techniques. The material ofthe dielectric 118 may include silicon oxide, silicon nitride, siliconoxynitride, boron nitride, high-k materials, or any combination of thesematerials. Examples of high-k materials include but are not limited tometal oxides such as hafnium oxide, hafnium silicon oxide, hafniumsilicon oxynitride, lanthanum oxide, lanthanum aluminum oxide, zirconiumoxide, zirconium silicon oxide, zirconium silicon oxynitride, tantalumoxide, titanium oxide, barium strontium titanium oxide, barium titaniumoxide, strontium titanium oxide, yttrium oxide, aluminum oxide, leadscandium tantalum oxide, and lead zinc niobate. The high-k may furtherinclude dopants such as lanthanum, aluminum. In an embodiment, thedielectric 118 may have a thickness ranging from about 2 nm to about 5nm and ranges there between, although a thickness less than 2 nm andgreater than 5 nm may be acceptable.

The conductor 120 may include a conductive material, such as metal. Forexample, the conductor 120 may include polycrystalline or amorphoussilicon, germanium, silicon germanium, a metal (e.g., tungsten,titanium, tantalum, ruthenium, zirconium, cobalt, copper, aluminum,lead, platinum, tin, silver, gold), a conducting metallic compoundmaterial (e.g., tantalum nitride, titanium nitride, tungsten silicide,tungsten nitride, ruthenium oxide, cobalt silicide, nickel silicide),carbon nanotube, conductive carbon, graphene, or any suitablecombination of these materials. The conductive material may furtherinclude dopants that are incorporated during or after deposition. Theconductor 120 may be deposited using typical deposition techniques, forexample, atomic layer deposition (ALD), molecular layer deposition(MLD), chemical vapor deposition (CVD), physical vapor deposition (PVD),and spin on techniques. The dielectric 118 and the conductor 120 may bepolished using a chemical mechanical polishing (CMP) technique until atop surface of dielectric 118 and the conductor 120 is substantiallycoplanar with a top surface of the second dielectric layer 116, asillustrated. Stated differently, top surfaces of the dielectric 118 andthe conductor 120 are substantially flush with the top surface of thesecond dielectric layer 116.

Referring now to FIG. 8, the dielectric 118 and the conductor 120 may berecessed until a top surface of the mask 110 in the first stack 204 isexposed. In the first stack 204, the dielectric 118 and the conductor120 may be removed. The first, second and third fourth openings 404, 406and 408 may each have an exposed top surface of the dielectric 118 andthe conductor 120. In an alternate embodiment, the mask 110 may also berecessed and a top surface of the semiconductor layer 108 is exposed inthe first stack 204.

A dielectric cap 122 may be formed in the first stack 204, and thefirst, second and third openings 404, 406 and 408. The dielectric cap122 may be formed using typical deposition techniques, for example,atomic layer deposition (ALD), molecular layer deposition (MLD),chemical vapor deposition (CVD), physical vapor deposition (PVD), highdensity plasma (HDP) deposition, or any suitable combination of thosetechniques. The material of the dielectric cap 122 may include siliconoxide, silicon nitride, silicon oxynitride, boron nitride, high-kmaterials, carbon doped silicon oxide, fluorine doped silicon oxide,boron carbon nitride, hydrogen silsesquioxane polymer (HSQ), methylsilsesquioxane polymer (MSQ), organosilicate glass (SiCOH), or anycombination of these materials. In an embodiment, the dielectric cap 122may include silicon nitride deposited using a chemical vapor depositiontechnique.

The dielectric cap 122 may be polished using a chemical mechanicalpolishing (CMP) technique until a top surface of each of the dielectriccaps 122 are substantially coplanar with the top surface of the seconddielectric layer 116, as illustrated. Stated differently, top surface ofthe dielectric caps 122 are substantially flush with the top surface ofthe second dielectric layer 116.

Referring now to FIG. 9, third dielectric layer 124 may be formed.Portions of the second dielectric layer 116 may be removed by patterningtechniques to subsequently be filled with a conductive material to forma first contact 520, a second contact 522, a third contact 524, and afourth contact 526. The first and second contacts 520, 522 may each havea bottom surface substantially flush with a top surface of the substrate102. The first and second contacts 520, 522 may each have a verticalsurface substantially flush with a side of one of the pair of sidewallspacers 112 of the high voltage transistor 202. The first, second, thirdand fourth contacts 520, 522, 524, and 526 may include polycrystallineor amorphous silicon, germanium, silicon germanium, a metal (e.g.,tungsten, titanium, tantalum, ruthenium, zirconium, cobalt, copper,aluminum, lead, platinum, tin, silver, gold), a conducting metalliccompound material (e.g., tantalum nitride, titanium nitride, tungstensilicide, tungsten nitride, ruthenium oxide, cobalt silicide, nickelsilicide), carbon nanotube, conductive carbon, graphene, or any suitablecombination of these materials. The conductive material may furtherinclude dopants that are incorporated during or after deposition.

In an embodiment, the first contact 520 and the second contact 522 maybe formed in the inactive region 200 and may each serve as a gate forthe high voltage transistor 202. At least one of the first contact 520and the second contact 522 may be active and turn on the high voltagetransistor 202. In an embodiment, the first contact 520 and the secondcontact 522 may be electrically connected.

The third and fourth contacts 524, 526, may be formed in the activeregion 300. The third and fourth contacts 524, 526, may each have abottom surface substantially flush with a top surface of the epitaxylayer 114. The third and fourth contacts 524,526, may each have avertical surface substantially flush with a side of one of the pair ofsidewall spacers 112.

The third dielectric layer 124 may be formed directly on the exposed topsurfaces of the structure 100, according to an exemplary embodiment. Thethird dielectric layer 124 may be made from an insulator material suchas an oxide, nitride, oxynitride, silicon carbon oxynitride, siliconboron oxynitride, low-k dielectric, or any combination thereof. Thethird dielectric layer 124 may be deposited using typical depositiontechniques, for example, atomic layer deposition (ALD), molecular layerdeposition (MLD), chemical vapor deposition (CVD), physical vapordeposition (PVD), and spin on techniques. In an embodiment, the thirddielectric layer 124 may include one or more layers. In an embodiment,the third dielectric layer 124 may have a vertical thickness, or height,ranging from about 30 nm to 100 nm, and ranges there between, although athickness less than 30 nm and greater than 100 nm may be acceptable.

The second dielectric layer 116 and the third dielectric layer 124 mayhelp insulate the first, second, third and fourth contacts 520, 522,524, 526 from each other, as illustrated.

Referring now to FIG. 10, a cross-sectional view of the structure 100 isshown of FIG. 9 is shown along section line AA. As described above, theinactive region 200 includes the high voltage transistor 202, whichincludes the semiconductor layer 108 of the high voltage transistor 202,surrounded by the pair of sidewall spacers 112 of the high voltagetransistor 202. The semiconductor layer 108 may serve as a channel ofthe high voltage transistor 202. The pair of sidewall spacers 112 mayserve as a gate dielectric of the high voltage transistor 202. The firstcontact 520 may be on an opposite side of the high voltage transistor202 than the second contact 522. The first contact 520 and the secondcontact 522 may be electrically insulated to serve as two independentgates of the high voltage transistor 202. Alternatively, the firstcontact 520 and the second contact 522 may be wired together. Theinactive region 200 may also include a first high voltage transistorsource drain region 600 and a second high voltage transistor sourcedrain region 602. The first high voltage transistor source drain region600 and the second high voltage transistor source drain region 602 arenot seen in the earlier figures due to the respective area ofcross-sectional views. The first high voltage transistor source drainregion 600 and the second high voltage transistor source drain region602 may be doped with dopants such as p-type dopants (such as boronand/or indium) or n-type dopants such as phosphorus, arsenic, and/orantimony). The dopants can be introduced in the first high voltagetransistor source drain region 600 and the second high voltagetransistor source drain region 602 by any known doping techniques suchas ion implantation followed by dopant activation anneal process.Patterning may be used during ion implantation to protect other regionsthat do not need those dopants.

The active region 300 includes the epitaxy layer 114 and the fin 104.The alternating lines of the epitaxy layer 114 and the fin 104 are thesource/drain regions of the FET 302. The dielectric 118 and the pair ofsidewall spacers 112 isolate conductor 120 from source/drain regions.The conductor 120 in a center of the active region 300 may be a gatewhich is used to turn on or turn off the FET 302. The conductor 120 inan outer portion of the active region 300 may serve as a dummy gate toisolate the FET 302 from another device on the structure 100.

An additional metal layer, which includes wires and electricalconnections, may be formed on the structure 100. The metal layer mayprovide connections to each of the first, second, third and fourthcontacts 520, 522, 524, 526, as well as the gate and the source/drainsof the high voltage transistor 202 and the FET 302.

The high voltage transistor 202 may operate via one or more of the twogates, which are the first contact 520 and the second contact 522, thechannel which is the semiconductor layer 108, first high voltagetransistor source drain region 600 and the second high voltagetransistor source drain region 602. The dielectric 112 in the inactiveregion 200 serves as the gate dielectric for the high voltage transistor202.

In order to simplify manufacturing of both CMOS FET and high voltagetransistors in the same process flow, this disclosure allows forsimultaneously manufacturing one or more high voltage transistors 202along with other CMOS FETs 302. The structures of the high voltagetransistor 202 and the CMOS FET 302 can be formed using the sameprocesses. For example, the pair of sidewall spacers 112 in the inactiveregion 200 may serve as the gate dielectric for the high voltagetransistor 202, while the pair of sidewall spacers 112 in the activeregion 300 may serve as an isolator between the conductor 120 and thesource/drain region and contacts of the FET 302. The first, second,third and fourth contacts 520, 522, 524, and 526 are formed by the sameprocess. The first and second contacts 520 and 522 each serve as a gateconductor of the high voltage transistor 202. Meanwhile, the third andfourth contacts 524 and 526 serve as contacts to the source/drainregions of the CMOS FET 302. The high voltage transistor may be used ina power converter for electronics which require a higher voltage, forexample 5V, vs a lower voltage used for CMOS FETs, for example 1V. Thereare other applications of the high voltage transistor.

As the semiconductor industry evolves, there is a benefit to reduce orcombine semiconductor manufacturer process steps. The present inventionmay allow for the manufacture of devices requiring high voltagetransistors, and CMOS FETs.

It may be noted that not all advantages of the present invention areinclude above.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The terminology used herein was chosen to best explain the principles ofthe embodiment, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method comprising: conformally depositing asemiconductor layer on a semiconductor substrate simultaneously in afirst region and a second region, wherein a top surface of thesemiconductor layer above an array of fins only in the second region isat a greater height than a top surface of the semiconductor layer in thefirst region, wherein the height is measured relative to a common planarsurface of the semiconductor substrate; forming a mask on thesemiconductor layer; simultaneously etching the semiconductor layer andthe mask in the first region to expose a top surface of thesemiconductor substrate to form a first stack, and the semiconductorlayer and the mask in the second region to expose a top surface of a finof the array of fins to form a second stack; simultaneously forming afirst pair of sidewall spacers on opposite sidewalls of the first stackand a second pair of sidewall spacers on opposite sidewalls of thesecond stack by conformally depositing a dielectric layer andanisotropically etching the dielectric layer from horizontal surfaces ofthe first stack and the second stack, wherein the first pair of sidewallspacers remains adjacent to the sidewalls of the first stack and thesecond pair of sidewall spacers remains adjacent to the sidewalls of thesecond stack; epitaxially growing a semiconductor material on a topsurface of the fin not covered by the second stack nor the secondsidewall spacers; recessing, simultaneously, the first stack and secondstack to remove the mask and expose a top surface of the semiconductorlayer in the second stack, wherein a portion of the mask remains abovethe semiconductor layer in the first stack, wherein after recessing, atop surface of the remaining portion of the mask in the first stack issubstantially flush with the top surface of the semiconductor layer inthe second stack; and simultaneously forming a gate in the first regionand source drain contacts in the second region, wherein the gate isadjacent to and in direct contact with at least one of the first pair ofsidewall spacers, and wherein the source drain contacts are in directcontact with the epitaxially grown semiconductor material.